1. Field of the Art
The present invention relates to a gasket of elastic material, such as rubber or similar for use in forming a seal between respective sealing surfaces of two members to be joined, the gasket for installation purposes being attached to the sealing surface of one of the members, and the sealing surfaces of the members being moved substantially parallel to each other for squeezing the gasket therebetween.
In connection with the assembly of concrete basins and other pipe-shaped products which are to be sealed by a gasket of elastomeric material, it is necessary to cover the gasket or one of the sealing surfaces with a lubricant for reducing the friction between the gasket and the joint member. This is of special importance in the cases where limited forces are available for compression, or where tolerances in the joint members may easily lead to the occurrence of breakage therein due to too high gasket pressure. However, the friction between rubber and e.g. concrete is so high that such an installation nevertheless involves large difficulties.
2. Prior Art Statement
There are previously known several gasket constructions which can facilitate the installation, said gaskets offering a satisfactory sealing. In U.S. Patent Application Ser. No. 883,615 instructions are given for a gasket cross-section including a core which is constructed from closely arranged lamellae which during the installation are angularly shifted for thereby reducing the height of the gasket, the elasticity of the rubber urging to revert the lamellae to their original position for thereby effecting the necessary packing pressure. In connection with fairly smooth sealing surfaces such a known gasket functions satisfactorily. If the sealing surfaces have, to the contrary, a very rough surface, it is very difficult to have the sealing surfaces slide along the rubber gasket.
Further, there are known structures seeking to eliminate the sliding between concrete and rubber, and for example in U.S. Pat. No. 3,510,140 there is suggested a gasket in which portions of the gasket profile during the installation is folded, a lubricant being provided between the folded portions. During installation the sliding will take place between the rubber surfaces of the gasket rather than between rubber and concrete. Such a known gasket structure functions fairly satisfactorily. but it suffers from the disadvantage that the lubricant may be applied immediately prior to the installation, the lubricant otherwise being apt to easily disappear during storage as well as being easily contaminated on site.
In addition, although such a known gasket offers a relatively easy installation of the members to be joined, it suffers from the disadvantage that the finished installed members may easily be separated since the gasket hardly offers any resistance when the joint members are influenced by forces seaking to urge them apart.
In SE-PS No. 78 00282-1 there is disclosed embodiments of sealing rings comprising a substantially triangular main portion and a relatively thin portion which from a point of connection extends across a conical sliding surface on the triangular main portion. Such a triangular main portion having a conical sliding surface is unfavourable in connection with joints which are to adopt large pressures, since only a minor portion of the core of the gasket will be utilized for sealing purposes in its final mounted position. Further, the patent specification only discloses embodiments in which a covering portion extends from the triangular core portion and together therewith define a pocket open in the longitudinal direction, a fact which includes that a predisposed lubricant will easily disappear due to evaporation or washing off if the gasket is not transported and stored with a special packaging.